Mineral oil containing alkyl polymethacrylate antifoamant



Unit d tat ate 7 Claims. Cl. 252-56) This application is a division ofmy copending application Ser. No. 79,499, filed Dec. 30, 1960, nowUnited States Patent No. 3,269,993.

The invention relates to new methacrylate antifoamants and to mineraloil compositions containing the same.

Conventional acrylate and methacrylate polymers are described in detailin US. 2,091,627. These conventional polymers are described to beespecially useful for improving the viscosity-temperature coefficient oflubricating oils. The conventional polymers are made by peroxide orozonide catalysis at 70100 C. Recently methods of making certainstereospecific polymers have been dis covered and reported; for example,a paper was presented at the April 1959 meeting of the American ChemicalSociety, Division of Paint, Plastics and Printing Ink Chemistry titled,Stereospecific Anionic Polymerization of Methyl Methacrylate, by W. B.Goode et al. This paper is reported in the divisions preprints on pagesl35-140. Syndiotactic, isotactic, block polymers and conventionalpolymersare described in this paper.

It has now been discovered how to make polymethacrylate antifoamants.Poly(methyl methacrylate) is not useful as an antifoamant inconventional or in any stereo form. Also, it has been discovered thatconventional polymers of longer chain alkyl methacrylate are not goodanti-v foamants. It has further been determined that syndiotactic longerchain alkyl polymethacrylates are not good antifoamants. Verysurprisingly, it has been found that isotactic alkyl polymethacrylatewherein the alkyl group has from 3 to about 14 carbon atoms are verygood antifoamants. Methacrylates, in general have good hydrolysisstability, superior, for example, to acrylates, and this good hydrolysisstability is an especially desirable characteristic for theirantifoamant use.

' It is an object of this invention to provide new polymers useful asantifoamant additives.

It is another object of this invention to provide new mineral oilcompositions having low foaming tendencies.

These and other objects of the invention will become apparent as thedetailed description of the invention proceeds.

. The new antifoamant polymer additives of the invention are isotactictype polymers. They can be made by homoploymerizing C to about Cpreferably C to about C alkyl methacrylates, or by copolymerizing 03-020alkyl methacrylates with methyl methacrylate or other (up to C alkylmethacrylates to give polymers averaging C to about C alkyl groups,preferably C to about C using anionic-initiated polymerization; forexample, Grignard-initiated polymerization. Suitable monomers useful formaking the homopolymers and copolymers of the invention can be selectedfrom the following illustrative but non-limiting list: methylmethacrylate, ethyl methacrylate, n-propyl methacrylate, isopropylmethacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl meth-Patented Sept. 5,1967

acrylate, n-amyl methacrylate, isoamyl methacrylate, nhexylmethacrylate, n-heptyl methacrylate, 2-ethylhexyl methacrylate, n-nonylmethacrylate, n-decyl methacrylate, Lorol methacrylate, oxotridecylmethacrylate, lauryl methacrylate, tallow methacrylate, etc. Lorolmethacrylate is a mixture of methacrylates made by esterifyingmethacrylic acid with a mixture of 3%C 6l%C 23 %C 11%-C and 2%Cstraight-chain alkyl alcohols.

The polymers of the invention are effective antifoaming agents when theyare employed in very low proportion, i.e. in amounts of less than 0.1%by weight based on the weight of the total hydrocarbon oil compositions.From 0.001% to 0.05% of the polymers is preferred but can be varieddepending on the nature of the oil. Heavy oils and oils containingfoam-inducing adjuvants require more of the polymer than do base oilswith lesser foaming characteristics. In addition to being employed inmineral lubricating oils per se as antifoamants, the methacrylatepolymers of the invention can be employed with compounded oilsgenerally, such as hydrocarbon oils containing additives such asviscosity index improvers, pour-point depressants, detergents, metaldeactivators, antioxidants, or extreme pressure agents, e.g. withphosphate-containing gear oils, corrosion-inhabited turbine oils, etc.In addition to being useful antifoamants for mineral lubricating oils,the isotactic polymers of the invention are useful antifoamants forhydraulic oils, automatic transmission oils, furnace oils, disel oilsand the like, i.e. mineral oils in general.

The invention is further illustrated but not limited by the followingexamples:

Example 1 This example describes the preparation of a conventionallauryl methacrylate/methyl methacrylate copolymer 72/28 molar ratio tobe used for comparison with an isotactic polymer of the invention as toantifoamant property. To a Coke bottle was charged 10 g. of laurylmethacrylate, 1.5 g. of methyl methacrylate, 0.0025 g. ofazobisisobutylronitrile catalyst and 12.5 g. of toluene solvent. TheCoke bottle was then capped and agitated in a rotating air ovenmaintained at a temperature of 68 C. for 48 hours. The crude'polymerproduct was purified by three separate precipitations from methanol withthe polymer being dissolved in hot benzene between methanolprecipitation. The purified polymer was dried at 45- 50 C. in a vacuumoven overnight. Dried polymer yield Was 10.9 g. A sample of this polymerwas submitted for elemental analysis yielding the following results.

Found: C, 73.7%; H, 11.2%. Calcd.: C, 73.5%; H, 11.4%.

Example 2 This example describes the preparation of a syndioactic laurylmethacrylate/methyl methacrylate copolymer of 72/28 molar ratio forcomparison with an isotactic polymer of the invention. To a glassreaction vessel was added 20 g. of lauryl methacrylate, 3 g. of methylmethacrylate and 0.32 ml. of triethyl boron (2 mole percent). Thereactants were mixed under nitrogen and cooled to ice bath temperature.Then the nitrogen was displaced with air and the reactants were allowedto react for 44 hours with occasional stirring of the reaction mixtureduring the first three hours. The polymer was purified by three separatesolved in hot benzene between methanol precipitations.

J) Then the purified polymer was dried at 50 C. in a vacuum ovenovernight. Dry weight of the polymer was 22.6 g. The syndiotacticity ofthe product was verified by infrared analysis. An elemental analysis ofthis purified polymer yielded the following results.

Found: C, 73.9%; H, 11.7%. Calcd.: C, 73.5%; H, 11.4%.

Example 3 This example describes the preparation of an isotactic laurylmethacrylate/methyl methacrylate copolymer of the invention having amolar ratio of 72/28. To a 500 ml. four necked flask fitted withnitrogen inlet and outlet stirrer, dropping funnel and thermometer wasadded 200 .ml. of toluene. The toluene and monomer mixture wereseparately bubbled with nitrogen for one hour and cooled to C. TheGrignard reagent consisting of 2.4 ml. of 3 molarphenyl-magnesiumbromide in diethyl ether was added to the toluene. Themonomer mixture, 20 g. of lauryl methacrylate and 3 g. of methylmethacrylate, was added dropwise to the reaction vessel over a period of26 minutes at such a rate as to keep the temperature of the reactantsbelow 5 C. The reactants were stirred for three hours at 2 C. thenpoured into methanol. The precipitated polymer was dissolved in hotbenzene and precipitated in methanol. This benzene-methanolprecipitation treatment was repeated two more times. The recoveredpurified polymer was dried under vacuum overnight giving a yield of 10.5g. of dried polymer. The isotacticity of this polymer was verified byinfrared analysis.

Example 4 This example describes the preparation of an isotacticpoly(n-octyl methacrylate) of the invention. The same type of apparatusused in Example 3 was used in this example. To the reaction fiask wasadded 150 ml. of toluene which was cooled to 5 C. under nitrogen. Then 2ml. of three molar phenylmagnesiumbromide in diethyl ether was added tothe toluene. The temperature of the reaction mixture was maintainedbetween about 3 C. and 5 C. while 17.87 g. of n-octyl methacrylate wasadded over a period of minutes. The reaction mixture was stirred for 5%hours, then left overnight before the work-up of the polymer. Thepolymer was precipitated from the reaction mixture by the addition ofmethanol, dissolved in hot benzene and reprecipitated from methanol,repeating the benzene-methanol precipitation two more times. Purifiedpolymer was dried in a vacuum oven at 50 C. overnight giving a 5.4 g.yield of dried polymer. The isotacticity of this polymer was verified byinfrared analysis.

Example 5 This example describes the preparation of an isotacticpoly(n-butyl methacrylate) of the invention. The same procedure as wasused for Example 4 was used in this example except as described below.The charge to the reactor was 200 ml. of dry toluene, 23 g. of butylmethacrylate and 4 ml. of 3 molar phenylmagnesiumbromide in diethylether. The monomer was added to the catalyst and toluene over a periodof 19 minutes and the reaction mixture was stirred at ice bathtemperature for 3 hours before being left overnight. The polymer waspurified and dried in the same manner as in Example 4 and the yield ofpurified dried polymer was 4.2 g.

Example 6 This example describes the preparation of another isotacticpoly(n-butyl methacrylate) of the invention. The procedure used in thisexample was the same as used in Example 5 except as described below. Thecharge to the reactor was 200 ml. of toluene, 21.9 g. of n-butylmethacrylate and 5.2 ml. of 3 molar ethylmagnesiumbromide in diethylether. Addition of the monomer to the catalyst and toluene took 27minutes. The polymerization time was 1 /2 hours after which time thereaction mixture was poured into methanol and the recovered polymerpurified and dried as described in Example 4. Yield of purified driedpolymer was 4.7 g.

Example 7 This example describes the preparation of a conventionalpoly(n-octyl methacrylate) for comparison with the correspondingisotactic polymer of the invention. To a Coke bottle was charged 19.8 g.of n-octyl methacrylate, 0.025 g. of azobisisobutyronitrile catalyst andml. of benzene. The Coke bottle was then stoppered and inserted into atumbling air oven for 5 days at 70 C. The reaction mixture was treatedwith methanol to precipitate the polymer and the polymer was purified inthe conventional manner as described in other examples above. The yieldof purified polymer was 15.6 g.

Example 8 This example describes the preparation of a conventionalpoly(n-butyl methacrylate) for comparison with the correspondingisotactic methacrylate of the invention. This example was carried out ina fashion similar to Example 7. The charge to the reactor was 14.2 g. ofn-butyl methacrylate, 0.025 g. of azobisisobutyronitrile catalyst and100 ml. of benzene. The yield of purified polymer was 8.4 g.

Example 9 This example describes the preparation of a conventionalpoly(2-ethylhexyl methacrylate) for comparison with isotactic polymersof the invention. This experiment was carried out in a fashion similarto Example 7. The charge to the reactor was 19.8 g. of 2-ethylhexylmethacrylate, 0.025 g. of azobisisobutyronitrile catalyst and 100 ml. ofbenzene. The yield of purified polymer was 18.2 g.

Example 10 This example describes the preparation of an isotacticpoly(n-amyl methacrylate) of the invention. This experiment was carriedout in a manner similar to that described in Example 3. 200 ml. oftoluene and 3 ml. of 3 molar phenylmagnesiumbromide in diethyl etherwere charged to the reaction flask. Nitrogen blanketi ng was used andthe toluene and catalysts were cooled to 1 C. Over a period of 22minutes, 16.5 g. of n-amyl methacrylate was added to the catalyst andtoluene maintaining the temperature between 3 and 5 C. The reactionmixture was stirred at 0 C. for 4 hours, then the polymer wasprecipitated in methanol. The recovered polymer was dissolved in hotbenzene and reprecipitated in methanol. This benzene and methanoltreatment was repeated two more times to purify the polymer. Thepurified polymer was dried in a vacuum oven at 50 C. overnight resultingin 6.4 g. of dry polymer.

Example 11 This example describes the preparation of a poly(nhexylmethacrylate) of the invention. This experiment was carried out in amanner similar to Example 10. The charge to the reactor was 200 ml. oftoluene, 14.7 g. of n-hexyl methacrylate and 2.8 ml. of 3 molarphenylmagnesuimbromide in diethyl ether. Addition of the monomer to thetoluene and catalysts was completed in 11 minutes. As in Example 10 thereaction time was 4 hours. The polymer was recovered, purified and driedin a similar manner to that described for polymer of Example 10. The dryweight yield of purified polymer was 7.6 g.

Example 12 This example describes the preparation of a laurylmethacrylate polymer of the invention. The toluene and the monomer usedin this example were purged by bubbling with nitrogen for 1 /2 hours.Similar apparatus and procedure was used as had been used in Example 3.To the flask was charged ml. of toluene (dried over sodium) and 2 ml. of3 molar phenylmagnesiumbromidein diethyl ether. The flask and contentswere cooled and when the temperature had dropped to 3 C. addition of20.5 g. of lauryl methacrylate was started. The temperature was kept bycooling between 3 and 5 C. and the addition of the monomer was completein 44 minutes. Stirring of the reactants was continued for a period of 2hours after which time the reaction mixture was poured into methanolcausing precipitation of a gummy polymer mass. The crude polymerrecovered from the methanol was added to benzeneand heated. Somedifficulty was encountered in putting the polymer in solution in hotbenzene, but this was finally accomplished. The polymer was thenprecipitated with methanol and washed with methanol. The procedure ofdissolving in hot benzene and precipitating from methanol was repeated 3more times to purify the polymer. The purified polymer was dried in a,vacuum oven overnight at 40 C., and 11.5 g. of dried polymer wererecovered. The isotaticity of this polymer was verified by infraredanalysis.

' Example 13 This example describes the .preparationof an isotacticmethyl methacrylate polymer. A sample of 900 ml. of purifiedtoluene'which had been bubbled with nitrogen to remove trapped oxygenfor 1 hour was added to a 2 liter, four-necked, round-bottom flask. Thetoluene was cooled to 1 C. using an ice bath and ml. of 3 molar,phenylmagnesiumbromide was added to the toluene. Then the addition of 50g. of methyl methacrylate monomer which had been nitrogen-bubbled likethe toluene, was begun dropwise with agitation of .the reaction mixture.The methyl methacrylatewas added slowly to keep the tem perature below 5C. and nitrogen blanketing was used during the entire procedure. Theaddition of the monomer was completed in 22 minutes. Polymerization wascontinued for an additional 5 hours and minutes at ice bath temperature.At the end of this time the reaction mixture Was poured into 6 liters ofpentane with vigorous stirring.

The polymer precipitated and was washed with additional Example 14 Thisexample describes the-preparation of an isotactic polymer from tallowmethacrylate which is a mixture of of monomers was added to the Grignardcatalyst over a period of 28 minutes at 4 C. This mixture of monomersconsisted of 5 g. of methyl methacrylate and 12.7 g. of laurylmethacrylate. The catalyst 2 ml. of 3 molar phenylrnagnesiumbromide indiethyl ether was added to 200 Example 16 This example describes thepreparation of a conventionl poly-(lauryl methacrylate). To a Cokebottle were charged 50 g. of lauryl methacrylate, 58 g. of benzene and0.029 g. of azobisisobutyronitrile catalyst. The Coke bottle was cappedand agitated in an air oven at 68 C. for 60 hours. At the end of thistime the reaction mixture was poured into methanol to precipitate agummy polymer. The precipitated polymer was dissolved in benzene andagain precipitated from methanol. This purification procedure wasrepeated 2 more times. The purified polymer was then dried in a vacuumoven overnight yielding 48.7 g. of purified dried polymer.

Example 17 This example describes the preparation of a conventionalpolymer from a mixture of n-octyl methacrylate and methyl methacrylatein 77/23 molar ratio. To a Coke bottle was added 17.5 .g. of n-octylmethacrylate, 2.5 g. -of 'methyl'methacrylate, 0.025 g. of'azobisisobutyronitrile catalyst and 100 ml. of benzene. The Coke bottlewas cappedand agitated for 5 days in an air oven at 70 C. At the end ofthis polymerization time the polymer was purified by the usual repeateddissolving in benzene and precipitating from methanol. Yield of polymerwas 16 .9 g.

. Example 18 This example describes the preparation of a conventionalmethyl methacrylate polymer. To a Coke bottle about 33% by weight of Cand about 67% by weight of C straight-chain alkyl methacrylates. Similarapparatus.

and procedure was used as was used in Example 3. To

and nitrogen blanketing was applied. To this toluene in the reactionvessel was added the Grignard catalyst which W was 3 ml. of 3 molarphenylmagnesiumbromide in diethyl ether. The tallow methacrylate monomerwas .purifiedby percolation over alumina to remove polymerizationinhibitor and a sample of this purified material 31.2 g was added to thereaction vessel over a 24 minute period at a rate to keep thetemperature between 05 C. After 4 hours during which time the reactionmixture was maintained at about 0 C. the reaction mixture was pouredinto methanol. The crude polymer was recovered from the methanol,dissolved in benzene and precipitated from methanol with this dissolvingand precipitation procedure being repeated two more times. The purifiedpolymer was then dried in a vacuum oven for 58 hours. Yield of driedpolymer was 22.8 g.

8 Example 15 This eXarnple d escrihes the preparation of a polymer ofthe invention prepared from a /50 molar ratio of lauryl methacrylate andmethyl methacrylate. Similar ap paratus and procedure was used as wasused in Example 3. The mixture of monomers was added to'the Grignardcatalyst over a period of 28 minutes at 4 C. This mixture was added 30g. of methyl methacrylate freshlydistilled,

100 cc. of carbon tetrachloride and 1.5 g. of 1be nzoyl .peroxide. TheCoke bottle was capped and heated at for 48 hours agitating in an airoven at '43 r.p.rn.

.The reaction mixture was diluted to ten percent solids (based onreaction of monomer) with carbon tetrachloride and used directly foranti-foamant evaluation.

' Table I below is a summary of the polymerization experiments and thecharacteristics of the polymers produced in the examples. The type ofpolymer, i.e isotactic, conventional or syndiotactic has been determinedfrom the method by which the polymer was made and for some oftheexamples has been verified by infrared analysis. Others working withpoly(methyl methacrylate) and using nuclear magnetic resonance studiesconfirm our polymer type designation such as that of Example 13. Theconventional polymers are syndiotactic but the term conventional hasbeen used to distinguish from polymers called syndiotactic which haveappreciably higher relative syndiotacticity as indicated by infrared anddifferential infrared analysis. .For a more detailed discussion of thissituation reference is made to copending application Ser. No. 79,671,filed Dec. 30, 1960, now United States Patent No. 3,252,949. In thiscopending application FIGURE 3 relative syndiotacticity is defined fromdifferential infrared values for two different types of polymers. Thiscurve also defines relative isotacticity if one reads 0 relativesyndiotacticity as relative isotacticity and 100 relativesyndiotacticityas a relative isotacticity of 0 which they are by definition. Preferredpolymers of the invention have greater than 60 relative isotacticity,more preferably greater-than 80 relative isotacticity. I

TABLE 1 Ex. Methacrylate Monomer, Sp. Vise 2 N o. Monomers 1 1llotleType of Polymer at 25 C Conventional.

1 LM-Lauryl methacrylate; MM-Methyl methacrylate.

2 Determined for 1% polymer in benzene.

3 Partly insoluble.

The anti-foam testing of isotactic polymers of the invention as comparedwith syndiotactic and conventional polymethacrylate is summarized inTable 11 below. In the tests 30 m1. of the oil composition being testedis added to a 100 ml. graduate. Nitrogen is bubbled through the oilsample at 0.2 cubic feet per hour from a sintered glass bubbling tubefor 5 minutes. At the end of this 5 minute period the volume of foam inmilliliters is taken as a measure of the anti-foam activity. The baseoil used was a solvent refined Mid-Continent petroleum oil having thefollowing properties:

Viscosity at 210 F., centistokes 10.39 Viscosity at 100 F., centistokes91.73 Flash point, Cleveland open cup, F. 450

preferably not more than about 10% by weight based on the mixture withthe methacrylate monomers.

Although the invention has been described in terms of specifiedembodiments which are set forth in considerable detail, it should beunderstod that this is by way of illustration only and that theinvention is not necessarily limited thereto since alternativeembodiments and operating techniques will become apparent to thoseskilled in the art in view of the disclosure. Accordingly, modificationsare contemplated which can be made without de parting from the spirit ofthe described invention.

Having thus described our invention, what we desire to claim and secureby Letters Patent is:

1. A mineral oil composition having low foaming characteristicscomprising a major portion of mineral oil and at least an amountsufficient to substantially reduce foaming in said oil but less than0.1% by weight based on said composition of isotactic alkylpolymethacrylate having an average in the range of 3 to about 14 carbonatoms in the alkyl group and a specific viscosity at C.

and 1% concentration in benzene in the range of 0.2 to 10.0.

2. A mineral oil composition having low foaming characteristicscomprising a major portion of mineral oil and 25 at least an amountsufficient to substantially reduce foaming in said oil but less than0.1% by weight based on said composition of isotactic alkylpolymethacrylate having an average in the range of 4 to about 12 carbonatoms in the alkyl group and a specific viscosity at 25 C. and 1%concentration in benzene in the range of about 0.5 to

about 6.0.

3. A composition of claim 2 wherein said polymethacrylate ispoly(n-butyl methacrylate).

4. A composition of claim 2 wherein said polyrnethacrylate isp0ly(n-amyl methacrylate).

5. A composition of claim 2 wherein said poly-methviscosity Index 103.4acrylate 1s poly(lauryl methacrylate) TABLE II Average Foam volume inmilliliters at various polymer Example Methaerylate Alkyl Type ofconcentrations 2 N o. Monomer 1 Chain Polymer Length 500 p.p.m. 300p.p.m. 200 p.p.m.

8. 9 Isotactic NF /MM 8. 9 Conventional 25 LM/MM 8. 9 syndiotacticn-0ctyl 8. 0 Isotactie F do 8. 0

2-ethylhexyl 8. 0 n-octyl/MM 7. 1 LM 1 6. 5 n-hexyl... 6. 0 n-nmyL. 5. On-butyl- 4. 0 do 4. 0 o 4. 0

Methy 1. 0 Methyl." 1.0 50 (l, 000) Base oil 50 1 LM means laurylmethacrylate; MM means methyl methacrylate 2 NF means no foam; B meanslarge bubbles; designation such 3.5 20 (150) means 20 m1. of foam at 150p.p.m. polymer concentration in oil.

It is seen from an examination of the data of Table II that theisotactic polymers of the invention are effective antifoamants; Whereas,the corresponding conventional and syndiotactic polymers are not.Preferred isotactic antifoamant polymers of the invention at aconcentration of 1% in benzene have specific viscosities at 25 C. in therange of 0.2 to 10.0, more preferably in the range of about 0.5 to about6.0.

Suitable antifoamants of the invention are also formed by copolymerizingmethacrylate monomers with other monomers such as styrene,acrylonitrile, acrylate, vinyl acetate, etc. The same polymerizationprocedure is used to prepare these isotactic polymers with thesemiscellaneous monomers as is used to prepare the isotactic methacrylatepolymers. The amounts of these other monomers should be restricted tonot more than 15% by Weight,

6. A composition of claim 2 wherein said polymethacrylate ispoly(n-octyl methacrylate).

7. A composition of claim 2 wherein said polymethacrylate is poly(laurylmethacrylate/methyl methacrylate) in 50/50 molar ratio, respectively.

DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Examiner.

1. A MINERAL OIL COMPOSITION HAVING LOW FOAMING CHARACTERISTICS COMPRISING A MAJOR PORTION OF MINERAL OIL AND AT LEAST AN AMOUNT SUFFICIENT TO SUBSTANTIALLY REDUCE FOAMING IN SAID OIL BUT LESS THAN 0.1% BY WEIGHT BASED ON SAID COMPOSITION OF ISOTACTIC ALKYL POLYMETHACRYLATE HAVING AN AVERAGE IN THE RANGE OF 3 TO ABOUT 14 CARBON ATOMS IN THE ALKYL GROUP AND A SPECIFIC VISCOSITY AT 25*C. AND 1% CONCENTRATION IN BENZENE IN THE RANGE OF 0.2 TO 10.0. 